The present disclosure relates to a power feeding apparatus and a wireless power feeding system each of which utilizes a non-contact power feeding system and supplies and receives an electric power in a non-contact (wireless) manner, and which can be applied to a storage body such as a chest of drawers or a storage box.
An electromagnetic induction system is known as a system for carrying out supply of an electric power in a wireless manner.
In addition, in recent years, a wireless power feeding and charging system using a system called a magnetic field sympathetic resonance system utilizing an electromagnetic resonance phenomenon has attracted attention.
In the non-contact power feeding system as the electromagnetic induction system which has already been generally used at present, a power feeding source and a power feeding destination (electric power receiving side) have to hold a magnetic flux in common. Thus, for the purpose of effectively feeding the electric power, the power feeding source and the power feeding destination have to be disposed in close proximity to each other. Also, axis alignment for the coupling between the power feeding source and the power feeding destination is also important.
On the other hand, the non-contact power feeding system using the electromagnetic sympathetic resonance phenomenon has advantages that it can feed the electric power at a distance as compared with the case of the electromagnetic induction system because of the principles of the electromagnetic sympathetic resonance phenomenon, and even when the axis adjustment is poor a little, the feeding efficiency is not reduced so much.
It is noted that an electric field sympathetic resonance system using the electromagnetic sympathetic resonance phenomenon is known in addition to the magnetic field sympathetic resonance system using the electromagnetic sympathetic resonance phenomenon.
In the wireless power feeding system of the magnetic field sympathetic resonance type, the axis alignment is unnecessary, and it is possible to lengthen the power feeding distance.
Now, the magnetic field generated by a coil in the wireless power feeding system is necessary for the transmission of the electric power. Also, the regulations for the intensity of the circumferential electromagnetic field are carried out in the form of laws and guidelines in countries from a viewpoint of interference with peripheral electronic apparatuses or protection of the human body.
A first technique disclosed Transistor Technology 2004. 2 Test Production of Non-Contact Power Feeding Type Switching Power Source Made On Experimental Basis by Shin Nakagawa pp. 195 to 205 (referred to as Non Patent Document 1 hereinafter), http://www.d.dendai.ac.jp/lab_site/dlab/2-3d-2/jiki.pdf (referred to as Non Patent Document 2 hereinafter) and a second technique disclosed in Japanese Patent Laid-Open No. Hei 10-163889 (referred to as Patent Document 1 hereinafter) are known as a technique capable of suppressing an influence of the magnetic field exerted on the outside in the wireless power feeding.
FIGS. 1A and 1B are respectively a view and a circuit diagram explaining the first technique capable of suppressing the influence of the magnetic field exerted on the outside.
With the first technique, coils CL1 and CL2 are wound around a magnetic material M1 to form a primary side transformer T1, and a secondary side transformer T2, respectively.
With regard to the transformers T1 and T2 for a non-contact power feeding type switching power source shown in FIG. 1A, a combination of the primary side transformer and the second side transformer is readily changed.
In the first technique, an idea that a transformer coupling portion is spatially separated becomes the starting point in the non-contact power feeding. When the transformer is used, a magnetic flux passes through the side of the magnetic material of the transformer and does not basically leak to the outside.
FIG. 2 is a view explaining the second technique capable of suppressing the influence of the magnetic field exerted on the outside, and is also a schematic view of an evaluation test apparatus.
In FIG. 2, reference numeral 1 designates a loop antenna, reference numeral 2 designates a drive power source, reference numeral 3 designates a ground contact point, reference numeral 4 designates an electromagnetic wave shield, reference numeral 5 designates magnetic field intensity measuring equipment, and reference numeral 6 designates electric field intensity measuring equipment.
In the first technique disclosed in Patent Document 1, the electromagnetic wave shield 4 is disposed in the vicinity of the loop antenna (transmission antenna) 1, thereby reducing the remote electric field intensity while the near magnetic field intensity is maintained.
The electromagnetic wave shield 4 is composed of a coil. One end of the electromagnetic wave shield 4 is opened, and the other end thereof is grounded to the ground GND at a ground contact point 3.